When using hand-held drilling machines it is very difficult to see and control the drilling direction. Thus the result often becomes more or less slanting holes that make mounting difficult and the result ugly. Also in other cases, as erecting posts, fences and door frames, brick laying and similiar works problems of making the construction right occur. The problems are often of the art that one, for instance when drilling, must be able to adjust the direction during ongoing operation.
The implements for direction control in use still to-day are mainly the same as in older times and based upon set squares, plumb-lines, levels and similiar utensils. The problems and detriments that accompany those primitive methods are well known. They are useless for continous control. They often demand helpers and do not give possibility of control in more than one direction.